Control of Japanese Beetle Grubs on a Golf Course Fairway, 1987

Six insecticides were evaluated on a golf course fairway at the Grove Park Inn near Asheville, N.C. The fairway consisted of Kentucky bluegrass and annual bluegrass maintained at a height of 2 inches with 0.5 inch of thatch. Soil type was mineral (0.7% organic matter) at pH 6.6. Treatments were applied 28 Apr (except the second application in the 2- + 2-lb Diazinon split treatment, which was applied 5 May) to 10- × 10-ft plots arranged in a randomized complete block design with 4 replications. Air temperature was 67°F and soil temperature was 58°F. Soil was moist at time of insecticide application. Granular formulations were applied using a hand-held glass shaker jar with a perforated top. Sprays were applied with a COz-pressurized backpack sprayer delivering 30 gal/acre at 40 psi using 8002 flat-fan nozzles. After application, all plots were irrigated with 0.5 inch of water. Plots were sampled on 21 May (23 DAT) by inspecting 1 sq ft of sod and all the underlying soil to a depth of 4 inches (most grubs were within 2 inches of the soil surface during both treatment and sampling). Two samples/plot were selected at random. All grubs (100% Japanese beetle grubs, 3rd instar) were counted and removed. Counts from the 2 samples were averaged and the data were transformed × + 0.5 prior to analysis.